HFSS Mesh setting with very thin layer graphene

I am new to HFSS. I am doing a HFSS design about graphene (0.34 nm) at 1 THz (3*10^5 nm wavelength). The layer is really small compared to the wavelength. The program just went wrong. But if I change the graphene thickness to 340 nm, which is 1000 times lager, the program will work.
I don't know why. Is it because that the mesh setting is not right? And how to set the mesh?
Thank you!

You can set the mesh size by assigning 'Mesh Operations' (right click on object -> Assign Mesh Operation). Use a minimum length setting to get the results you want (e.g. 0.01nm).

I'm not sure if that will solve your problem, let us know.

Good Luck!

Perhaps the model of graphene at such a small thickness is not correct?
Are the electrical properties of graphene at 0.34nm the same as graphene at 340nm?

what do u mean by wrong? is there any error?
btw, at that scale you can use semistatic approximation.

This problem is quite challenge, since your layer thickness is less than 1/10000 wavelength. The mesher might have a limit of max/min element size ratio and won't mesh it correctly if its too thin. Even though it meshed successfully, to get a accurate answer will take you a while. I assume your problem is an open problem, then the PML or ABC will have trouble for this kind of issue as well. Special techniques has to be developed to address this. Google some papers for graphine and FSS (frequency select surface) for some modeling hints.

How do you model the Graphene?